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Earth, Moon, and the Sun

Earth is doing two things at once

A day and a year are not the same. Earth is doing both right now.

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The idea

Earth sits on a ring round the Sun. An arrow shows its spin.
Step 1 of 4
  1. Earth sits on a ring round the Sun. An arrow shows its spin.
  2. One full turn of the arrow is one day.
  3. Earth also moves forward along the ring.
  4. One full trip round the ring takes about 365 days.

The rule

Earth turns once a day. It goes round the Sun once a year.

Earth's axis is the line through its two poles.

  • Rotation is turning on its own axis. One turn takes about 24 hours.
  • Revolution is going round the Sun. One trip takes about 365 days and 6 hours.

Earth turns from west to east. So the Sun seems to rise in the east.

The turning makes day and night. The trip round the Sun does not.

Jump to lesson

This track

  1. 0 Start here
  2. 1 Earth is doing two things at once
  3. 2 The Moon keeps one face turned to us
  4. 3 When three line up, one shades another
  5. 4 The Moon shades a patch of Earth
  6. 5 Earth shades the Moon
  7. 6 Why it is not every month
  8. 7 One is safe to watch, the other never is
  9. 8 Checkpoint: motions, the Moon and eclipses
  10. 9 Why the Sun seems to move
  11. 10 Day here, night there
  12. 11 The star that stays still
  13. 12 Checkpoint: the turning sky
  14. 13 The night sky changes through the year
  15. 14 The tilt makes the seasons
  16. 15 The longest and shortest days
  17. 16 Checkpoint: the year, the tilt and the seasons
  18. 17 The big picture
  19. 18 Track quiz

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